A wide variety of military application computers implement the Military Standard 1397B Type D or E interface for purposes of input and output (I/O). In brief, the type D interface is based on asynchronous serial data transfer using a 10 MHz clock and bipolar .+-.3.25 volts nominal. The type E interface is based on asynchronous serial data transfer using a 10 MHz clock and bipolar .+-.0.6 volts nominal. For a more detailed description of the interface specifications, see MIL-STD 1397B, Mar. 3, 1989, which is herein incorporated by reference. Of special interest is Section 5.3 concerning the Type D interface, and Section 5.4 entitled "Type E NATO low-level serial interface."
Prior to being placed in the field, testing of these computers is typically carried out on a simulator. While simulators may be custom designed for any specific computer, it is desirable to use a simulator that incorporates industry standard features and components. In this way, the cost of the simulator is minimized, the flexibility in design of the simulator is increased and the simulator may be used for a variety of application computers. One such industry standard feature is the VMEbus architecture, which is well known in the art. Unfortunately, VMEbus architecture is based on parallel I/O transfer. In order for a computer implementing the Type D/E interface to interface with a VMEbus architecture (simulator), it is necessary to convert I/O data streams to appropriate asynchronous serial formats.